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직사각형 밀폐공간내에 기체연료 옆면 누출시 가연혼합기 생성에 관한 연구
정낙규 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1
Theoretical analysis is applied to obtain the basic information for the prevention of explosion in a rectangular enclosure with gaseous fuel leak. Characteristics of flammable mixture formation such as distribution of flow and fuel mass fraction at various locations in the enclosure are determined for the following parameters : leak location, leak velocity and aspect ratio. As the leak velocity and leak time increase, the flammable mixture extends faster and wider. The higher leak location is the futher mass transfer is downward due to the gravitational force. Aspect ratio of the rectangular enclosure also affects the formation of flammable mixture proportional to the leak time and the leak velocity.
정낙규,김진홍,오율권,김창오,강승현 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.2
One of the ways to reduce abroad dependence for energy is to utilize solar energy when we are now confronted with not only insufficiency of natural resources but also the serious problems of environmental pollution. Therefore, full attention must now be paid to the development of solar energy system as alternative energy. To achieve this, solar hot water supply system was established at Chosun university, Gwang-ju, and experimental data were obtained based on meterological data and solar radiation. This study has been used the monthly mean values of the daily measurements obtained by data acquisition software Labview. This study shows Gwang-ju is a good region for the utilization of solar energy.
정낙규,김진흥,김창오 대한설비공학회 2004 설비공학 논문집 Vol.16 No.12
This study investigated the improvement effect of a small portion of surfactant on the supercooling and the phase change temperature of TMA 30 wt% clathrate compound when surfactant is added to the clathrate compound. The experiments are carried out under various conditions; the concentration of additive ranges between 0.08∼0.12 wt% and the temperature of heat source ranges between -8 and -6℃. The experimental results show that the phase change temperature with the surfactant of 0.1 wt% is lower by 1℃ than TMA 30 wt% and the supercooling is reduced by 10℃.
직사각형 밀폐공간내에 기체연료 밑면 누출시 가연성 혼합기 생성에 관한 연구
정낙규,김호영,Chung, N.K.,Kim, H.Y. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.4
Numerical method is applied to predict the time variation behavior of flammable mixture formation in a two dimensional enclosure from the beginning of gas leak. Additionally experimental method is used to consider qualitative aspects. Characteristics of flammable mixture formation such as distribution of flow and fuel mass fraction at various locations in the enclosure are determined for the following parameters: the various locations of leak at the bottom and aspect ratio of the enclosure. In the case of gas leak with small leak velocity from the bottom of enclosure gravitational force affects the formation of flammable mixture. Aspect ratio of the enclosure also affects the formation of flammable mixture. The volume of the region of recirculating flow is dominant factor affecting the formation mixture.
정낙규 조선대학교 동력자원연구소 1992 動力資源硏究所誌 Vol.14 No.1
From the fundamental point of view, one dimensional model on the spherical flame propagation in the spherical combustion chamber has been developed under laminar flow condition. This model is made up of a set of unsteady partial differential equations based on the spherical and radial one-dimensional coordinate. To confirm the validity of the model, the pressure of the combustion chamber, the position of the flame front and velocity of unburned gas were measured. Then, the calculation results were carefully compared with the experimental data and the agreements between them were good. Furthermore, the temperature of burned gas was measured by the Laser Rayleigh Scattering method.
축냉재 포접화합물의 열물성에 관한 실험적 연구 : 충전량 변화 Variations of Charging Conditions
하옥남,김진홍,정낙규 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.1
본 연구에서는 축냉재로서 에너지의 합리적 이용을 위한 건물공조용 축냉시스템에 적용이 가능한 TMA-물계 포접화합물의 농도와 충전량의 변화에 따른 상변화온도, 비열 및 과냉도를 실험을 통하여 다음과 같은 결론을 얻었다. (1) 냉열원온도 -5。C에서 상변화온도는 5.4。C 이상으로서 적절함을 확인하였다. (2) 상변화온도는 충전량이 많을수록 높아지는 것을 확인하였다. 위의 실험결과로부터 TMA-포접화합물은 건물공조용 축냉재로서의 열물성을 갖는다고 판단된다. The objective of this paper is to investigate the thermal properties of TMA-clathrate compound applicable to cold storage system for residential air-conditioning in order to use energy reasonably. Especially, the test tube experiments are performed to compare and analyze the concentration of TMA-clathrate compound, the temperature of heat source, and the phase change temperature, specific heat and subcooling characteristics according to the variation of charge capacity. The result are summarized as follows:1) -5。C is proper as the temperature of heat source because the temperature of phase change is above 5.4。C, 2) the phase change temperature appears higher as the charge capacity is larger. Thus, it appears that TMA-clathrate compound has thermal properties as the cold storage medium for residential air-conditioning.
정낙규,김진홍,김창오,강승현,정종현 조선대학교 에너지.자원신기술연구소 2004 에너지·자원신기술연구소 논문지 Vol.26 No.2
Clathrate compound is suitable for cooling applications as it possesses latent heat in the range of 5-12C, has a cooling storage capacity 2.3 times as large as that of the conventional chilled water. Because clathrate compound is a cooling medium with high thermal density, air-conditioning systems using clathrate compound are expected to substantially reduce cooling medium transportation costs and make an important contribution to energy savings, with attendant benefits in reducing CO_(2) emissions. But, supercooling phenomenon in the phase change process of water cause to increase the cooling capacity and to decrease COP of the refrigerator. Thus, the improvement of supercooling and thermal properties as phase change temperature are expehmentally investigated by comparing TMA30wt% clathrate compound with TMA30wt% clathrate compound that some additives are added.
정낙규,김진홍,김창오 朝鮮大學校 機械技術硏究所 2005 機械技術硏究 Vol.8 No.1
This study is investigated the supercooling improvement and the cooling characteristics of the TMA clathrate compound including TMA(Tri-methyl-amine, (CH3)3N) of 25 wt% with additive as a low temperature storage material at -6℃ heat source. The additive is ethanol of 0.1. 0.3 wt% and 0.5 wt%. The results showed that as the concentration of ethanol is increased, phase change temperature, the supercooling and retention time of liquid phase are decreased. Especially, TMA 25 wt% clathrate compound with ethanol of 0.5 wt% has the average of phase change temperature of 3.8℃, supercooling of 0.9℃ and retention time of liquid phase for 6 minutes in the cooling process. From the results of this study, TMA 25 wt% clathrate compound with ethanol showed higher phase change temperature than water and supercooling repression effect.
정낙규,김진흥,오율권,김창오,박호진,강승현 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.2
One of the ways to reduce abroad dependence for energy is to utilize solar energy when we are now confronted with only insufficiency of natural resource but also the serious problems of environmental pollution. Therefore, full attention must now be paid to the development of solar energy system as alternative energy. To achieve this, solar hot water supply system was established at Chosun university, Gwang-ju, and experimental data were obtained based on meterological data and solar radiation. This study has been used the monthly mean values of the daily measurements obtained by data acquisition software Labview. This study shows Gwang-ju is a good region for the utilization of solar energy.